W210's and I assume W211's come with plastic panels (usually 2) on the underside. Some times called anti-noise panels. To change the oil the old fashioned way you'll need to remove the front one. There are 4 fasteners near the centerline. Two near the bumper and two at the engine cross member. The rear two are shared by the smaller second panel. In addition there are 3 near the front of each wheel. 8mm socket or wench.

The drain plug is on the right side of lower oil pan. If you are going to drain pick up a seal from dealer. Goes under drain plug. Torque is 30Nm and size is 13mm. Torque on filter housing is 25Nm.

Jack stands are fine but use on a hard level surface such as concrete. Also. chock one on the wheels on the ground in both directions. If you don't have hard level surface, then ramps are a safer choice. In a pinch, some people drive one front wheel up on to a curb to gain some clearance. Depends on the neighborhood.